Ultra short wave system



Oct. 28, 1941. N. E. LINDENBLAD 2,260,529

ULTRA SHORT WAVE SYSTEM Filed June 19, 1957 2 Sheets-Sheet l A/R FAN BLOWER I--STOF/LAMENT faam/r ANUDE VOLTAGE SUPPLY CUOL/NG 4 FL UID SUPPLY FOR ANODE GRID LEAD ciw, 1

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k /f i' CONDE/ISEE INVENTOR /V/LS E. L/NDENBLAD ATTORNEY Oct. 28, 1941 N. E. LINDENBLAD ULTRA SHORT WAVE SYSTEM Filed June 4`19, 1957 2 sheets-sheet 2 @amar INVENTOR N/L E. DENBLAD BY ATTORNEY Patented Oct. 28, 1941 ULTRA SHORT WAVE SYSTEM Nils E. Lindenbla'd, Port Jefferson, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application June 19, 1937, Serial/No, 149,054

30 Claims.

The present invention relates to improvements in ultra high frequency amplifier circuits.

One of the objects of the invention is to provide an improved ultra high frequency amplifier -system which is easily balanced or neutralized against self-oscillation, and wherein only a large relative misadjustment of one circuit component with respect to the other circuit components will initiate oscillations.

Another object is to provide a relatively simplified mechanical construction for an ultra high frequency amplifier system, which is less costly to construct than conventional water-cooled circuits of the type wherein the radio frequency circuit is required to carry high voltage direct currents.

A further object is to provide a high frequency amplifier system in which there is no stray capacity from the anode of the amplifier vacuum tube to other parts of the system.

A feature of the invention lies in the use of a grounded anode amplier, wherein the anode of the vacuum tube is by-passed to ground for radio frequency energy, through a relatively large capacity, such as by means of a blocking condenser.

Another feature, which considerably simplifies the mechanical design and thus insures more stable electrical performance, is that the electrodynamically active elements of the tube (in this case grid and filament) are so arranged that they v act cophasally,

' Another feature of the invention resides in the use of a plurality of power amplifier vacuum tubes arranged symmetrically around one or more centrally located radio frequency circuits, with a single network or dummy tube yfor balancing or neutralizing purposes. This feature serves the triple function of increasing the power output of the system, minimizing the lengths of the lead connections to the amplifier tubes, and maintaining perfect circuit symmetry for all the amplifier tubes.

Other objects and features, and their advantages will appear from a reading of the following description, which is accompanied by drawings, wherein:

Fig. 1 illustrates diagrammatically, an ultra high frequency amplifier constructed in accordance with the principles of the invention;

Fig. la illustrates a very general equivalent circuit given only for the purpose of exposition;

Figs. 2, 3 and 4 illustrate views, partly diagrammatic and partly in section, of three different embodiments of the invention.

Like parts throughout the figures have been designated by like reference numerals.

Referring to Fig. 1 in more detail, there is shown an ultra high frequency balanced amplifier system comprising an electron discarge device 3 located within a grounded metallic substantially cylindrical container 2.` The anode I of the amplifier device 3 is coupled to ground by means of plate 4 which is capacitively coupled to the container 2. The filament of device 3 is effectively connected to one end of a hollow metallic tube 5 which surrounds the lead I5 to the grid and the filament heating leads, not shown. The other part of the balanced system comprises a dummy circuitor artificial network, shown within the circular dotted line, simulating the reactance condition of the electron discharge device rand consisting of a pair of condensers arranged in the form of three metallic plates 8, 9 and I0. The center plate 9 simulates the grid and is connected to an input lead I6, one outer plate I0 simulates the anode and is grounded at container 2, and the other outer plate 8 simulates the filament of a live'electron discharge device and is connected to one end of hollow tube 5, the spacing between the plates 8, 9 and I0 determining the capacity between the elements of the dummy.

At a distance corresponding to resonance of the grid circuit, the grid lead l5 for the device 3 and the lead I6 for the dummy are short circuited by strap 6. An input circuit 1 is inductively coupled to the leads I5 and I6 within hollow tube 5 by means of a loop, as shown, the center of the loop being grounded to prevent eventual pushpush effects in the amplifier system from being` capacitively fed back into the input circuit. The push-push effects hereinabove mentioned refer to the excitation that could be exchanged between the wires I5, I5 and loop 1 due to capacitive coupling. By grounding loop 'I at its center, Il thus prevent the loop from assuming a floating potential. It will thus be obvious that the input tov the amplifier system is in push-pull relation, while the output is not in push-pull relation.

Another short circuiting strap II is provided across the grid leads I5 and I6 at a distance from the open end of cylindrical conducting tube 5 equal to half the length of the operating wave, in order to simulate a direct connection between the open end of tube 5 and the leads I5 and I6 insofar as these leads are considered to be in parallel or push-push relation. By push-push I refer to the condition wherein both leads I5 and `I6 are in phase and act as one conductor of such a length that at the orifice of cylinder 5 a sh0rt- I beentdesignated in i respectively.y

potential. with the lament is intrinsic with the response l ofthe tube 3 to the excitation it receives. uthe plate or' anode'is' grounded, the lament is circuit effect is obtained. Since the hollow cylinl -drical conductory is part of the tank circuit, the

grid and the corresponding element of the network will ride on top of its oscillations. This is because the grid and the corresponding element of the network are made to have the same potential as the shell surrounding the two-wire line just as if they were directly .connected to the shell, and thus rideon the shell potential. The

reason the grids cannot be directly connected is because such a connection would prevent any c Vsort of input feed.

The tank or tuned output circuit for the amiplier 3 consists of the anode capacity between plate 4 andthe container .2 and -a path of uniformly distributed inductance traced over the inner surface of container 2 and the outer surface of tube 5. The path of this tank circuit is traced by the arrows on the drawings. tank circuit is accomplished by means of movable the containerZ and tube 5.

Output energy vis derived from the amplifier system by 4means of connection I4 which is adjustable over the length of tube 5. f

l Before proceeding with a description of*V the operation vof the push-pulll amplifier system, it should lbe jnoted that the use of a dummy or articial network is essential to the operation of the particular system illustrated in the drawing,

otherwise it would not be possible to derive output energy from the tube 5. Since both the cathode olfjdevi'ce 3 and the corresponding connection for the `dummy from plate Bare connected to the 'same location on the tube 5, it should be evident that the hollow sleeve-like tubular element 5 would be at neutral 'potential and the currents would flow in the same direction in these filament connections if a live electron discharge device were substituted for the dummy or artificial network. This will be moreapparent from a consideration of Fig. la, which illustrates in a very general y,manner the' equivalent circuit of Fig. 1, exceptfor the omission of any reference to' the arrangement for short-circuiting the push-push oscillations. The elements in Fig 1a corresponding to those in Fig. l have been given the same Tuning `of the 1 l lmetallic sliders I2, rI3 which are simultaneously l adjustable (unicontrolled) over the lengths of I reference numeralsv except fora prime designation. Thelament to Vgrid and the grid to anode capacities of the electron discharge device have In the operation of the balanced amplifier sys- 1 tem, the lament of the electron discharge deg vice swings at radio frequency potential instead 1 of the'anode. 3 phase with the filament but at a higher'amplitu'de, the grid connections being superimposed on The grid of device 3 also swings in the filament connections without prohibiting neutralizing or balancing. Putting it another way,

anyI potential '(such as from push-pullexcita# tion), in addition to the shellpotential, will under correct phase condition add up with the shell lThe in phase condition of the grid Fig. 1ct as F-G and G-P,

Since i in phase with the grid; the filament excites the l v the circuit requires.

spacings between plate 9 and plates 8 and I0 are variable in nature to provide any desired degree of neutralization or balance. The excitation introduced on leads I5 and I6 by input circuit 'I causes device 3 to pass electron current which causes the filament of the electron discharge device to oscillate. The inductive coupling between input circuit I land leads YI 5 and AI 5 minimizes back reaction. Slider or strap 6 across the leads I5 and I6 in push-push so that the push-push drop pull relation. The strap I I tunes the leads I5 and I6 in push-pull so that the push-pushdrop is Zero where the leads I5 and I5 emerge at the open end of tube 5,l or with -a controllable amount (either inductive or capacitive) as the need of In this way, there is obtained a control of the regeneration which can offset the vdegenerative effect of the steady capacitive drop through the lament to grid and grid to anode capacities of device 3.

Figs. 2 and `3 illustrate arrangements conn structed inv accordance with` the principles of the invention, which have been successfully tried out in practice.` In these two figures all back reaction or 'capacity' push-pushV feed-back effect, has beenv eliminateddue to the use of double concentric lines. n l

AIn one embodiment used in accordance with Fig. 2, the electron discharge device 3 was an RCA type A-21'74 water-cooled vacuum tube.` The two lament leads from the device 3 are brought out'to opposite'. points on the metallic tube 5 which extends on both sides of the device, each lead terminating in half cylindrical metal plates Il capacitivelycoup-led toitube 5". Mica spacers, not shown, separate the plates Il from the tube 5". The nlament leads are thus by-passed to ground. It should be noted that the filament leads extend in one direction within tube 5" while the push-pull input leads I5 andl I3 extend in an oppositedirection. 4The output tank circuit of Fig. 2 comprises two sections connected in parallel, each section being electrically turnable by metallic sliders I2, I3 contacting the outer surface o'f metallic tube 5" and the inner surface of grounded metallic container 2". Short-circuitinglslider II is here shownV capacitively vcoupled to ground.

An important advantage of the circuit of Fig. 2 is that the anode' of device 3 does not carry high radio frequency voltage. Consequently, where water cooling of the anode is required, as here shown in the drawings, there is nohigh radio frequency potential connected to theV water supply. Heretofore, precautionary measures had to be taken to -connect kthe water cooling system to voltage nodal points on the radio frequency circuit. By means of the4 present invention I'eliminate the use of high direct current potentials on the radio frequency circuit.

In Fig. 3, the connections to the grid of device 3 and plate 9 of the dummy comprise portions of parallel hollow tubes coupled to the loop, shown in dotted lines, connected to input circuit l. `'The currents in tubes I5" and I5" flow on the outside of these tubes from the grid of device 3 and plate 9 to the apertures I'I through which vthe input loop passes, and through the aperturesto the inner surface of these tubes down to the input circuit. The arrows indicate the directions of the currents and the surfaces on which they flow. The input loop is here perfectly shielded and so coupled to the lines I5. and I6 that the original input lines 'I for push-pull operation form a perfectly con* I5" and I6 which are tinuous connection all the way to the grid and plate 9; the only requirement being that the loop from apertures I'I to bridge 25 be one-quarter wavelength long and the surge impedance of the inner conductors be equal to the surge impedance between its shells.v The quarter wavelength distance indicatedl in Fig. 3 provides a high impedance for currents on the upper outside part of tubes l5" and I6 which tend to flow on the outside of these tubes past the apertures I7, and forces these currents to continue their flow on the inside of the tubes below the apertures. Small shield flaps I8 at the loop cross-over at apertures I'I, I'I are provided to prevent capacity between the input leads within tubes I5" and IB and the output system.

Fig. 4 illustrates how a plurality of grounded anode ampliers can be connected in parallel relation in order to obtain larger power amplification. A single dummy or artiiicial network, shown inv dotted lines, is employed for use with all the electron discharge devices 3. By surrounding the central metallic tube I8 with devices 3, 3 in the manner indicated in the drawing, the connections to the devices are reduced to a minimum.

By means of the present invention, I am able to control the degree of neutralization or b-alance so that I can get regeneration or degeneration. That is, I can change a strictly balanced amplier to a regenerative amplifier, either by unbalancing the condensers of the dummy or articial network, or by changing the location of the half wavelength short circuit strap used for suppressing push-push oscillations. I have been able to obtain as much as a 10:1 power ampliiication by means of the invention.

It should be understood that the term ground used in the specification and claims is intended to mean any point or surface of zero or iixed radio frequency potential.

It should also be understood that the invention is not limited to the particular arrangements shown and described since various modiiications may be made without departing from the spirit and scope of the appended claims.

What is claimed is:

1. An ultra high frequency amplifier system comprising an electron discharge device having anode, cathode and grid electrodes, a tuned output circuit including an electrically conductive envelope surrounding said electron discharge device, a connection of low impedance to energy of the operating frequency from said envelope to ground, a capacitive connection from said anode to said envelope for by-passing radio frequency energy, and means for exciting said grid at a higher amplitude than an in phase with said cathode.

2. A balanaced ultra high frequency amplifier system comprising an electron discharge device having anode, cathode and grid electrodes, a dummy network having capacitive elements whose characteristics simulate those of the electrodes of said electron discharge device, a tuned output circuit including an electrically conductive envelope Asurrounding said electrondischarge device and dummy network, a connection of 'low impedance to energy of the operating frequency from said envelope to ground, an input circuit for applying potentials of opposite instantaneous polarities to said grid and the corresponding element of said network, and connections coupling said anode and the corresponding element of said network to ground for providing a path of low impedance for radio frequency energy.

3. A balanced ultra high frequency amplifier system comprising an electron discharge device having anode, cathode and grid electrodes, a network having capacitive elements Whose characteristics simulate those of the electrodes of said electron discharge device, an input circuit for applying potentials of opposite instantaneous polarities to said grid and the corresponding element of said network, a tuned output circuit including an electrically conductive envelope surrounding said electron discharge device and said network, a connection of low impedance to energyof the operating frequency from said envelope to ground; connections coupling said anode and the corresponding element of said network to ground for radio frequency energy, connections from said cathode and the corresponding element in said network to substantially the same potential point on said amplifier system, and means for substantially preventing said grid and its corresponding element in said network from having in-p-hase oscillations superimposed thereon.

4. A system in accordance with claim 3, including means for varying the capacity of the elements in said network.

5. A balanced ultra high frequency amplier system comprising an electron discharge device having anode, cathode and grid electrodes, a network having capacitive elements whose characteristics simulate those of the electrodes of said electron discharge device, an input circuit for applying potentials to said grid and the corresponding element of said network, which poten.- tials are out-oi-phase with respect to each other, a metallic envelope surrounding said device and network, connections from said anode and the corresponding element of said network to said envelope, a connection from said envelope to ground, whereby radio frequency energy from said anode is by-passed to ground, means coupling said cathode to a different point on said envelope, whereby said envelope comprises a tuned circuit, a slider for varying the effective length of said envelope for tuning said tuned circuit, and a connection to said tuned circuit for deriving output energy therefrom.

6. An ultra high frequency amplifier system comprising an electron discharge device having anode, cathode and grid electrodes, a tuned output circuit including an electrically conductive envelope surrounding said device, a connection of low impedance to energy of the operating frequency from said envelope to ground, a capacitive connection from said anode to said envelope providing a low impedance path for the radio frequency energy, and water cooling means for said anode.

7. A balanced ultra short wave ampliiier system comprising an electron discharge device having anode, cathode and grid electrodes, a capacitive network comprising a central metallic plate and first and second outer plates on opposite sides of and capacitively coupled to said central plate, the capacity between said `anode and grid being substantially equal to that between said central and first plates, the capacity betweenl said cathode and grid being substantially equal to that between said central and second plates, means for varying the spacing between said plates, an input circuit coupled to said grid and central plate, a tuned output comprising a metallic envelope surrounding said discharge device and capacitive network, and individual connections of low impedance to radio frequency energy from said anode and first plate to ground.

8. A balanced ultra short wave amplifier system comprising an electron discharge device having anode, cathode and grid electrodes, a capacitive network comprising a central metallic plate and first and second outer plates on opposite sides of and capacitively coupled to said central plate, the capacity between said anode and grid being Substantially equal to that between said central and first plates, the capacity between said cathode and grid being substantially equal to that ble--` tween said central and second plates, individual connections coupling said anode and rst plate to ground, a hollow metallic tube, individual parallel connections extending from said grid and central plate along a portion of the length of and within said tube, a short-circuiting strap within Said tube across said last connections at a predetermined distance from thepoints 'of entry of said last connections in said tube, and an input circuit inductively coupled to said last connections for supplying thereto potentials of opposite instantaneous polarities. I

9. A balanced ultra short wave amplifier system comprising an electron discharge device having anode, cathode and grid electrodes, a capacitive network comprising a central metallic plate and rst and second outer plates on oppositev sides of and capacitively coupled to said central plate, a capacity between said anode and grid being substantially equal to that between said central and rst plates, the capacity between said cathode and grid being substantially equal to that between said central and second plates, individual connections coupling said anode and rst plate to ground, a hollow metallic tube, individual parallel connections extending from said grid and central plate along a portion of the length of and within said tube, a short-circuiting strap within said tube across said last connections at a predetermined distance from the points of entry of said last connections in said tube, and an input circuit inductively coupled to said last connections for supplying thereto potentials of opposite instantaneous polarities, said input circuit including a loop of wire within said tube and having the legs of said loop extend-ing parallel to and adjacenit said parallel connections, and a connection from the electrical center of said loop to ground.

10. A system in accordance with claim 8, characterized in this that said electron discharge de-1 vice and capacitiver network are symmetrically arranged on opposite sides of said metallic tube, said short-circuiting strap being adjustable over the lengths of said last connections.

11. A balanced ultra short wave amplifier system comprising an electron discharge device having anode, cathode and grid electrodes, a capacitive network comprising a central metallic plate and first and second outer plates on opposite sides of and capacitively coupled to'said central plate, the capacity between said anode and grid being substantially equal to that between said central and first plates, the capacity between said cathode and grid being substantially equal to that between said central and second plates, individual connections coupling said anode and rst plate to ground, a hollow metallic tube, individual parallel connections extending from said grid and central plate along a portion of the length of and within said tube, a short-circuiting strap within said tube across said last connections at a predetermined distance from the points of entry of said last connections in said tube, means coupling said cathode and second plate to substantially the saine potential point on said -metallic tube,` andy an input circuit inductively coupled to said last connections for applying thereto potentials of opposite instantaneous polarities.

13. A balanced ultra short wave amplifier system comprising an electron discharge device having anode, cathode and grid electrodes, a capacitive network comprising a central metallic plate and rst Vand second outer plates on opposite sides of and capacitively coupled to said central plate, the capacity between said anode and grid being substantially equal to that between said central and first plates, the capacity between said cathode and grid being substantially equal to that between said central and second plates; individual connections coupling said anode and iirst plate to ground, a hollow metallic tube, individual parallel connections extending from said grid and central plate along 'a portion of the length of and within said tube, a short-circuiting strap within said tube across said last connections at a predetermined distance from the points of entry of said last connections in said tube, another short-circuitingstrap `within said tube across said last connections at a distance, electrically, of substantially one-half the length of the operating wave from the points of. entry of said last connections in said tube, means coupling said cathode and second plate to substantially the same potential point on said metallic tube, and an input circuit inductively coupled to said last connections.

13. A balanced ultra short wave amplier systern comprising an electron discharge device having anode, cathode and grid electrodes, a capacitive network comprising a central metallic plate and rst and second outer yplates on opposite sides of and capacitively coupled to said central plate, the capacity between said anode and grid being substantially equal to that between said central 'and first plates, the capacity between said cathode and grid being substantially equal to that between said central and second plates, individual connections coupling said. anode and iirst plate to ground, a hollow metallic tube, Said electron discharge device and networkr being symmetrically arranged externally of said tube and between the ends thereof, individual parallel connections extending from said grid and central plate in one direction along the'length of and within said tube, a short-circuiting strap within said tube across said vlast connections at a predetermined distance from the points of entry of lsaid last connections in said tube, another shortcircuiting strap within said tube across said last vconnections at a distance, electrically, yof sub-- stantially one-half the length of the operating wave from the points of entry of said last connections in said tube, means coupling said cathode and second plate to substantially the samev potential point on said metallic tube, cathode heating leads extending within said tube in a direction opposite to that in which said parallel connections to said grid and central plate extend, an input circuit inductively coupled to said parallel connections, and an output circuit including the outer surface of said metallic tube.

14. A balanced ultra high frequency amplifier system comprising an electron discharge device having anode, cathode and grid electrodes, a capacitive network comprising a central metallic plate and rfirst and second outer plates, means `for varying the spacing between said plates for enabling the capacity between said first and central plates to simulate the capacity between said anode and grid and the capacity between said second and central plates to simulate the capacity between said grid and cathode, a metallic tubular substantially completely enclosed envelope surrounding said electron discharge device and network, a hollow metal tube positioned concentrically within said envelope, said device and network being located in the space between said two metal tubes, a capacitive connection from said anode to said envelope, a co-nnection from said first plate to said envelope, a connection from said envelope to ground, connections from said cathode and second plate to vpoints of substantially the same potential on said inner metal tube, whereby the inner surface of said envelope and the outer surface of said inner tube form a tuned circuit, means for varying the effective length of said tuned circuit, and an input circuit for applying out-of-phasepotentials to said grid and central plate. Y

15. A balanced ultra high frequency amplifier system comprising an electron discharge device having anode, cathode and grid electrodes, a capacitive network comprising a central metallic plate and first and second outer plates, means for varying the spacing between said plates for enabling the capacity between said firSt and central plates to simulate the capacity between said anode and grid and the capacity between said second and central plates to simulate the capacity between said grid and cathode, a metallic tubular substantially completely enclosed envelope surrounding said electron discharge device and network, a hollow metal tube positioned concentrically within said envelope, Said device and network being located in the space between and on opposite sides of said two metal tubes, a capacitive connection from said anode to said envelope, a connection from said first plate to said envelope, a connection from said envelope to ground, connections from said cathode and second plate to points of substantially the same potential on said inner metal tube, whereby the inner surface of said envelope and the outer surface of saidv inner tube form a tuned circuit, metallic sliding means contacting said two surfaces for varying the effective length of said tuned circuit, an output circuit coupled to at least one of said surfaces, and an input circuit for applying alternating potentials of opposite instantaneous polarities to said grid and central plate- 16. A balanced ultra high frequency amplifier system comprising an electron discharge device having anode, cathode and grid electrodes, a capacitive network comprising a central metallic plate and first and second outer plates, means for varying the spacing between said plates for enabling the capacity between said first andcentral plates to simulate the capacity between said anode and grid and the capacity between. said second and central plates to simulate the capacity between said grid and cathode, aI metallic tubular substantially completely enclosed envelope surrounding said electron discharge device and network, a hollow metal tube positioned concentrically within said envelope, said device and network being located in the space between and on opposite sides of said two metal tubes, a capacitive connection from said anode to said en velope, a connection fromsaid first plate to said envelope, a connection from said envelope to ground, connections from said cathode and sec- Vond plate to points of-Y substantially the same potential on said inner metal tube, whereby the inner surface of said envelope and the outer surface of said inner tube form a tuned circuit, metallic sliding means contacting said two surfaces for varying the effective length of said tuned circuit, an output circuit coupled to at least one of said surfaces, and an input circuit for applying out-of-phase potentials to said grid land central plate, said input circuit including a pair of parallel hollow conducting tubes extending within and parallel to the length of said inner metal tube, and a loop of wire inductively coupled to said conducting tubes, one leg of said loop being within and insulated from one-of said parallel conducting tubes and the other leg being within and insulated from the other of said parallel conducting tubes for similar length portions of said conducting tubes, there being a strap connecting the ends of said legs through apertures 1 tubes at the points of connection to said grid and 4 central plate.

18. In a high frequency system, a first circuit comprising a loop of wire, and a second circuit comprising a pair of parallel hollow, electrically conducting tubes, said loop of wire being so arranged that one leg thereof is insulatingly positioned within and parallel to one of Said tubes, while the other leg of said wire is insulatingly positioned within and parallel to the other of said tubes, said legs being connected to-. gether at one of their adjacent ends by a strap of wire extending through apertures in said tubes, in order to form said loop, means for exciting the legs of said loop of wire with out-ofphase alternatingpotentials, a balanced circuit coupled to said tubes at substantially symmetrical points thereon located beyondthe strap of said loop, and means for shortfcircuitingy the outer surfaces of said tubes at points below said strap located at a distance from said strap equal Asubstantially to one-quarter the length of the operating wave, whereby substantially coupling is effected between said loop and said tubes. i

19. A balanced ultra high frequency amplifier system comprising an electron discharge device having anode, cathode and grid electrodes, a network having capacitive elements whose 'characteristics simulate those of the electrodes of said electron discharge device, an input circuit for applying potentials to said grid and the corresponding element of said network, which potentials are out-of-phase with respect to each other, a metallic envelope surrounding said device and network, connections from said anode and thecorresponding element of said network to said envelope, a connection from said envelope to ground, whereby radio frequency energy from said anode is by-passed to ground, means coupling said cathode to a different point on said envelope and the corresponding kelement of said a slider for varying the effective length of said plates.

envelope for vtuning saidI tuned circuit, and a connection to said tuned circuit for deriving output-energy therefrom.,

20. A balanced yultra short wave amplifier system ,comprisingA an electron discharge device having. anode, cathode and grid electrodes, -a

Y ,capacitive network comprising a central metallic plate andfirst and second outer plates on Aopposite sides of and capacitively coupled to said central plate, the capacity between said anode andgrid being substantially equal to that between said central and rst plates, the capacity.

length of and within said tubea short-circuiting lStrap Within said tube across .said last connections at a predetermined distance fronr the points o f entry of said last connections in said tube, andan input circuit inductively coupledt o said` last connections for suppl-ying thereto potentials of opposite instantaneous polarities, said input circuit including a loop of wire within said tube and having the vlegs of said loop eX- tending parallel to and adjacent said parallel connections, and a connection from the electrical center of said vloop to ground.

21. In an amplier, an electron discharge device having anode, cathode and grid electrodes, another devicehaving elements whose characteristicssimulate those of the electrodes of said electron discharge device, means for grounding the anode ofy said electron discharge device and thegcorresponding element of said second' device through a path of low impedance to'energy of the operatingfrequency,means for causing the instantaneous potentialv ony said grid and on the element-cn.e said vsecond device corresponding to said grid to vary, respectively, in accordance with the instantaneous potential of said cathode and that element of said second device which corresponds to said cathode, a source of alternating voltage, and means for superimposing opposite phase potentials from said source on said grid v and that element o said secondv device which correspondsto said grid. Y i M2,2.. In an amplifier, an electron discharge device havingzanode-,j cathode and grid electrodes, another device having elements whose characteristics:V simulate those of the electrodes of said electrondischarge device, a resonant output circuit connected between said cathode and the corresponding element. of saidsecond device, means `bi1-passing said anode and the element of said second device corresponding to said anode to ground, means for causing the voltage on said grid and the element of said-second device correspending to saidgrid to follow voltage fluctuations of said cathode andits corresponding element,'and means for-independently applying an input voltageV in phase opposition between said rgrid and its corresponding element so that the grid-cathode voltage iseffectively varied vto produce an,v amplified `signal in said output circuit.

23..` In anamplifier, an electron discharge device having' anode, `cathode and grid electrodes, another device havingcelements whose characteristics simulate those. ov the. electrodes of said electron, dischargev device, means for applying signal voltages infphaseopposition between said ioA grid and that element of said second device which corresponds to said grid, .means for effectively vgrounding said yanode and that element of said seconddevice which corresponds to. said anode `withrespect to said signal voltage, a circuit between said cathode andy that element of said second device which corresponds to said cathode, means for impressing a direct current potential between said anode and cathode, means for obtaining an amplied output voltage from said cathode circuit, and. means for superimposing the voltage of said cathode circuit on said grid and its corresponding element.

24. In an amplifier system, a tank circuit comprising a hollow outer conductor and av hollow inner conductor within said outer conductor and coupled thereto, a connection from ground to said outer conductor, an electron discharge device amplifier having an anode, a gridand a cathode, meansl coupling said anode to said outer conductor, an input circuit, means Within said inner .conductor couplingsaid grid to said input circuit,

and an output circuit coupled to said inner conductor of said tank.

25,. In an amplier system, a tank circuit havingY substantially 'uniformlydistributed inductance and capacitance and comprising a pair of coaxial conductors suitably connected together, a connection from ground to the outer conductor of'rsaid pair, a multi-electrode electron discharge device amplifier having an ano-de, a grid and a cathode, means for capacitively coupling said anode to ground, an input circuit, and circuits including a connectionirom said input circuit to said grid for excitingY Said tank circuit, and for exciting Said; grid at; higher radio frequency potentials than but inyphase with saidcathode, and an output4 circuit coupled to, said' tank circuit.

2,6.y In anamplier system, a, tank circuit having substantially uniformly distributed inductance and capacitance and comprising a pair'of coaxial conductors suitably connected together, a` connection from ground to the outer conductorof' said pair, a multi-electrode electron ,dis-

charge device amplifier having an ano-de, a grid and a cathode,l means for capacitively coupling said anode to said outer conductor througha path; Of-Y 10W impedance to energy of the operatingA frequency, input circuit, and circuits including a connection from said input circuit to -saidV grid for inductively excitingy said tank circuitand for exciting.; said grid at higher radio frequencyv potentials than but in phase with the cathode, and an output',circuitcoupled to the inner conductor of saidtank.

2'7. An ultra high frequency amplifier system the corresponding velement of,vr said second device throughv apathof'low impedance to energy oi the operating frequency, meansI for causing the instantaneous,potentialonsaid grid and on; the

element of said second device corresponding to said grid to vary, respectively, in accordance with the instantaneous potential of said cathode and that element of said second device which corresponds to said cathode, an input circuit comprising a source of alternating voltage, means for superimposing opposite phase potentials from said source on said grid and that element of said second device which corresponds to said grid, and means for deriving output current from a portion of said amplifier which is entirely separate both from said input circuit and from the connections extending from said input circuit to said grid and to the corresponding element of said second device.

29. In a short wave amplifier circuit, an electron discharge device having an anode, a cathode and a grid, a network having capacitive elements whose characteristics simulate those of the electrodes of said electron discharge device, connections including a section of line having an outer conductor and an inner conductor for respectively coupling together the anode and cathode electrodes of said device to corresponding elements of said network, said outer conductor forming part of a resonant circuit, means for maintaining the connection between said anode tials to said grid and its corresponding element in said network. I

30. In an amplifier system, a tank circuit comprising a hollow outer conductor and a hollow inner conductor within said outer conductor and coupled thereto, said hollow conductors being coupled together at one end, a connection from ground to said outer conductor, an electron discharge device amplifier having an anode, a grid and a cathode, a network having capacitive elements whose characteristics simulate those of the electrodes of said device, means coupling said anode and the corresponding element of said network to said outer conductor, an input circuit, connections within said inner conductor coupling said grid and the corresponding element of said network in opposite phase to said input circuit, individual connections from said cathode and the corresponding element of said network to a location on said inner conductor appreciably removed from said one end, and an output circuit coupled to said tank.

NJLS E. T .INDETNBLADL 

